Antioxidant-containing textile lubricant, process for preparing nylon tire cord therewith and the resulting cord



United States Patent 3,397,081 ANTIOXIDANT-CONTAINING TEXTILE LUBRI- CANT, PROCESS FOR PREPARING NYLON TIRE CORD THEREWITH AND THE RESULT- ING CORD Thomas C. Mayberry, Wilmington, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware N0 Drawing. Filed Sept. 11, 1964, Ser. No. 395,887 Claims. (Cl. 117--139.5)

ABSTRACT OF THE DISCLOSURE A textile lubricating composition consisting of about 2 weight percent of the low temperature reaction product of diphenylamine and acetone having a melting point of 85 to 95 C., about 5 to 30 weight percent of a pentato septa-ester of a fatty acid having 12 to 16 carbon atoms in its chain and a condensation product of one mol of sorbitol and 30 to 40 mols of ethylene oxide, and the remainder coconut oil.

The present invention relates to textilelubricating compositions that resist degradation and the deposition of resinous materials on heated surfaces that they contact.

In the preparation of yarns suitable for tire cords, it is necessary to apply a lubricant to the yarn to permit processing of the yarn with a minimum of difficulty. As is well-known to the art, the selection of a suitable lubricant composition is not readily made because of the many diverse requirements imposed on the lubricating composition by the nature of the particular yarn and the manner in which the lubricated yarn is utilized. Of the many stringent requirements that the lubricating composition must meet, acceptable high-temperature processability is one of the most important. Of particular concern in hightemperature processing is the formation of hard, insoluble resins on heated surfaces.

Various organic compounds, for example, aryl amines, heterocyclic nitrogen compounds and bis-phenols are known to be used as antioxidants. However, the problem of finding a suitable material to minimize or eliminate high-temperature resin formation of an otherwise suitable textile lubricant is exceedingly difficu'lt. The material must be soluble in the lubricant to be useful and, further, must be compatible with the components of the lubricating composition. As is known, the selection of a material to stabilize lubricating compositions against thermal attack in an oxidative atmosphere is somewhat akin to the selection of a catalyst; that is, suitability cannot be determined by mere surmise or apparent function and must be established by trial. In practice, it is found that many supposedly suitable materials are essentially ineffective and that many others provide such marginal improvement as to be worthless for commercial application. With respect to commercial application, it is well-known to those skilled in the art that even apparently small improvements in high speed processes can have great significance, especially where the improvement contributes to longer trouble-free operation.

It is Ia primary object of this invention to provide :a textile-treating composition suitable for the preparation of tire yarn in a high-temperature process.

Another object is to provide a process for producing cord yarn having a finishing lubricant thereon.

These and other objects are attained in accordance with the present discovery in a composition of about 2 weight percent of the low temperature reaction product of diphenylamine and acetone having a melting point of 85 to 95 C., about 5 to 30 weight percent of a pentato 3,397,081 Patented Aug. 13, 1968 ice,

septa-ester of a fatty acid having 12 to 16 carbon atoms in its chain and a condensation product of one mol or sorbitol and 30 to 40 mols of ethylene oxide, and the remainder coconut oil. This composition is applied to yarn filaments during their manufacture.

In the conventional manufacture of yarn from polyhexamethylene adipamide, polycaproamide or other known nylon, or copolymer thereof, to be used for tire cord purposes, the yarn comes into contact with a plurality of heated rolls. In one typical process nylon polymer is melt-spun and the resulting filamentary strands are passed around a roll having at least one surface immersed in a bath of lubricating finish. The strands leaving the finish roll are converged by means of a guide. The yarn is then fed by a feed roll to a draw pin and then to first stage draw rolls. In this step part of the total drawing that is to occur is applied. The yarn then passes over a heated tube and from there to second stage draw rolls where the remainder of the draw is imparted. The drawn yarn is then wound in the conventional manner. The heated tube referred to can serve to preheat the yarn as it passes thereover to the second stage draw rolls. A typical hot tube temperature is in the range of about 185-190 C. The second stage draw rolls are heated to about 225 C. This high temperature serves to volatilize part of the finish that is present on the yarn and aggravates oxidative conditions, resulting in gum or resin formation. The resin tends to coat the hot draw rolls, and in a short time this can become serious enough to break yarn ends. To avoid breakage heretofore it has been conventional to stop the process after a short period of operation and clean the rolls. By use of the finish composition of the present invention, the periods between work stoppages for cleaning purposes are materially lengthened thereby reducing the chance of broken ends occurring and increasing the economy of production. It is believed that compositions of this invention have greater stability under the conditions of operation whereby resin formation and deposition are inhibited.

The compositions of this invention are prepared by simple mixing of the components to produce a homogeneous solution. Each of the components employed is commercially available land can be used in this invention as obtained without special treatment. For example any commercially available coconut oil can be used although a refined grade is preferred. Similarly the low temperature reaction product of diphenylamine and acetone having a melting point of to C. is commercially available, for example as Aminox, a proprietary product of Naugatuck Chemical Company.

The esterified condensation component also is known, and may be prepared by reacting an ethylene oxide with sorbitol at elevated pressures in the presence of a suitable catalyst such, for example, as an alkali metal hydroxide and then esterifying the reaction product. A number of related products and detailed procedures for their preparation have been disclosed by Brown in US. Patent No. 2,418,752.

The condensation products disclosed herein are prepared in a similar fashion except that 30 to 40 mols of ethylene oxide are reacted with one mol of sorbitol. This reaction product is esterified with a fatty acid, for example a mixture of oleic and lauric acids, preferably in a ratio of 4 mols of oleic acid to 1 mol of lauric acid. Preferably, 5 or more mols of fatty acid are used for each mol of the condensation product to obtain the pentato septa-ester. The sorbitol/ethylene oxide condensates are formed in the presence of a small amount of water and on esterification such compositions can react with up to at least seven equivalents of fatty acid. When seven equivalents of fatty acid are used to esterify these condensates, the product is referred to as a septa-ester. The resulting esterified product is characterized by a free hydroxyl number of about 30 to 110, i.e., the condensation product is only partially esterified. Mixture of such esters can also be employed. The esters of the sorbitol-ethylene oxide condensates may be used in amounts of about and 30 percent with the higher percentage being preferred because of wetting action, static protection, and because, if desired, they may be readily emulsified in water. The esterified sorbitol-ethylene oxide condensate is preferably a mixture of two separately prepared materials, i.e. part being esterified with a mixture of acids and part being esterified with a single acid, the condensates also differing in that different mol ratios of the reactants may be used.

-In utilizing a composition corresponding to that of this invention except for the diphenylamine-acetone product, in a high temperature process, it was found that a resin was formed on heated surfaces in a relatively short period of time, thus necessitating frequent stoppage of the process for removal of the resin. Accordingly, to determine the effectiveness of various materials, compositions were made by incorporating various additives in the base lubricant and determining the time required for resin formation to occur upon contact with a hot surface. The procedure used is:

A stock solution of a lubricating composition is prepared by mixing, by weight, 68.2 parts of a refined coconut oil, parts of a material prepared by condensing 1 mol of sorbitol with mols of ethylene oxide and esterifying the condensate with 5 mols of a 4.1 mixture of oleic and lauric acids (free hydroxyl number of 90-110), 10 parts of a material prepared by condensing 1 mol of sorbitol with mols of ethylene oxide and essentially completely esterifying the condensate with oleic acid (free hydroxyl number of 30) and, as an antibacterial agent, 1.8 parts of o-phenylphenol. To samples of the stock solution various antioxidants are added in amounts sufficient to provide 2 percent by weight, based on the total weight of the resulting solution. T wo-tenths of a gram of each sample is placed in a 6-centimeter diameter aluminum dish and heated at 225 C. in a forced-draft oven, and the time required for resin formation is recorded. Using this procedure it has been found that a sample which contains no additive forms a resin within 1 hour, while the composition of this invention does not form a resin until after about 19 hours. The next best sample, one containing polymerized 1,2 dihydro 2,2,4 trimethyl quinoline, forms a resin in about 11 hours. Among the large number of anti-oxidants tested and found to be unsuitable were hydroquinones, naphthyl amines, diphenyl amines, hindered phenols, aldehydeamine condensation products and bis-phenols.

The following example is given to illustrate practice of the present invention.

EXAMPLE I The previously described stock solution having dissolved therein 2% by weight, based on the total weight of the solution, of the low-temperature reaction product of diphenyl amine and acetone having a melting point of 8595 C. is applied to freshly-spun, 4700-denier, 140- filament nylon yarn by advancing the yarn over a roller rotating in a finish trough. The yarn from the finish trough contains 1.8% by weight, based on the weight of the yarn, of the composition. The yarn is then led to a draw zone where the yarn is drawn using a pair of draw rolls heated to a temperature of 225 C. The process is 4 operable for 3 weeks before the buildup of resin on the heated draw rolls requires removal and provides a highquality yarn suitable for reinforcing rubber tires.

When the yarn is treated with the previously described stock solution to which no antioxidant has been added, the process becomes inoperable, due to excessive broken filaments, within 24 hours.

It will be appreciated that this discovery can be employed in conjunction with other means that further lengthen process operability, without departing from its scope.

I claim:

1. A finish composition for yarn consisting essentially of, by weight, about 2 percent of the low temperature reaction product of diphenylamine and acetone having a melting point of to C., about 5 to 30 percent of a pentato septa-ester comprising at least one fatty acid containing 12 to 16 carbon atoms in its chain and the condensation product of a mol of sorbitol and 30 to 40 mols of ethylene oxide, and the remainder coconut oil.

2. A finish composition according to claim 1 in which the fatty acid portion of the ester is a mixture of oleic and lauric acids in a molar ration of 4: 1.

3. In the preparation of nylon yarn for tire cord in which nylon polymer is melt-spun to produce a plurality of filamentary strands, the resulting strands are coated with about 1 to 3 percent of a finish composition consisting essentially, on a weight basis, of about 5 to 30 percent of a pentato septa-ester comprising at least one fatty acid containing 12 to 16 carbon atoms in its chain and the condensation product of 21 mol of sorbitol and 30 to 40 mols of ethylene oxide, and the remainder coco- .nut oil, the strands are collected to a yarn and the yarn is drawn and contacts highly heated surfaces, whereupon resinous materials deposit on those surfaces, the improvement comprising including in the finish composition about 2 percent, based on the weight of the resulting composition, of the low temperature reaction product of diphenylamine and acetone having a melting point of 85 to 95 C.

4. A process according to claim 3 in which the fatty acid portion of the ester is a mixture of oleic and lauric acids in a molar ratio of 4:1.

5. Nylon tire cord yarn having on the surfaces of its filaments about 1 to 3 weight percent of a composition consisting essentially, by weight, of about 2 percent of the low temperature reaction product of diphenylamine and acetone, about 30 percent of a pentato septa-ester comprising at least one fatty acid containing 12 to 16 carbon atoms in its chain and the condensation product of a mol of sorbitol and 30 to 40 mols of ethylene oxide, and the remainder coconut oil.

References Cited UNITED STATES PATENTS 2,706,189 4/1955 Pruitt et al. 26045.95 3,097,111 7/1963 Danielson 1l7l 62 3,248,258 4/1966 Coats 117-l38.8

OTHER REFERENCES Handbook of Material Trade Names, Zimmerman and Layine, TP 151 25, 1953, C. 3 (Copy in Group p. 43, 8 lines from the bottom of Col. 2, pertinent.

WILLIAM D. MARTIN, Primary Examiner.

T. G. DAVIS, Assistant Examiner. 

